Speed change mechanism

ABSTRACT

A speed change mechanism for providing a high gear ratio between the input and output members in which all of the gear members have a standard gear tooth form. A carrier member is drivingly connected to one of the members and rotatably supports a pair of pinion gears eccentrically mounted relative to each other on the carrier. One ring gear is secured to a stationary housing and meshes with one of the pinions and a second ring gear drivingly connected to the other member and meshes with the other pinion. A third pinion gear which is an idler member in the system meshes with both of the other pinions through dual tangencies at the pitch diameters of the pinion gears.

United States Patent Ogawa I [451 Dec. 12, 1972 [54] SPEED CHANGEMECHANISM- [72] Inventor: Fremont T. Ogawa, Royal Oak,

Mich.

[713] Assignee: General Motors Corporation,

. Detroit, Mich.

[22] Filed: June 30,1971

[21] Appl.No.: 158,169

[52] U.S.Cl...... ..74/803 [51] Int.Cl .....F16h1/28 [58] Field ofSearch ..74/803 [56] References Cited UNITED STATES PATENTS 2,868,037l/l959 Hindmarch ..74/803X 2,955,487 10/1960 Malley ..74/803 3,453,9077/I969 Noguchietal. ..74/803 FOREIGN PATENTS OR APPLICATIONS 32,7491/1924 Denmark ..74/803 Primary Examiner-Arthur T. McKeon Attorney-W. E.Finken et al.

[5 7] ABSTRACT A speed change mechanism for providing a high gear ratiobetween the input and output members in which all of the gear membershave a standard gear tooth form. A carrier member is drivingly connectedto one of the members and rotatably supports a pair of pinion gearseccentrically mounted relative to each other on the carrier. One ringgear is secured to a stationary housing and meshes with one of thepinions and a second ring gear drivingly connected to the other memberand meshes with the other pinion. A third pinion gear which is an idlermember in the system meshes with both of the other pinions through dualtangencies at the pitch diameters of the pinion gears.

3 Claims, 2 Drawing Figures SPEED CHANGE MECHANISM This inventionrelatesto speed change mechanisms and more particularly to speed changemechanisms providing a largeinput to output speed ratio in whichstandard tooth formed gearing is used. 7 r The present inventionprovides a large speed ratio between the input and output members of aspeed change mechanism through the use of standard gear tooth forms in acompound planetary gearing arrangement. In the preferred embodiment thecarrier member is drivingly connected to the input shaft and one ringgear is drivingly connected to the output shaft. A second ring-gear issecured to a stationary housing and providesa reaction member-for theplanetary gearing. A pair of pinion gears are rotatably mounted on aneccentric shaft secured to the carrier and mesh with the first andsecond ring gears respectively. A third pinion gear is also rotatablymounted on the carrier and meshes with the other two'pinions at thepitch diameters thereof. To provide the high speed ratio between inputand output, one of the ring gears has more teeth than the other andsince the gear teeth have a standard tooth profile one ring gear has alarger diameter than the other. The eccentric shaft in the carrierpermits the center line of one of the pinions to be located radiallyoutsidethe-center line of the other pinion thus permitting the pinionsto mesh with the larger and smaller ring gear, respectively. Thetwopinion gears mesh with the idler pinion which has its pitch diameter solocated as to be tangent to the' pitch diameters of both the piniongears. In the prior art gearing arrangements in which planetary gearingis used to provide a large gear by a ball bearing 28 and has integrallyformed thereon a hub 30 which forms a portion of a planet carriergenerally designated 32.

the hubs 30 and 34.

ratio, a non-standard gear tooth form and accurately aligned gearclusters have been used. The present invention permitsthe use ofstandard gear tooth forms and avoids the use of cluster gears.

It is an object of this invention to provide in animproved'planetarytype speed change mechanism a compound planetarygearing arrangement utilizing stan dard tooth forms on all of thegearmembers and to eliminate the necessity for alignment of clusters.

It is another object ofthis invention to provide in an improved speedchange mechanism a compound planetary gearing arrangement-in which thecarrier member rotatably supportsa pair of standard tooth form planetarygears on an eccentric shaft member and an idler gear meshing with thefirst mentioned pinion gears on the pitch diameters thereof, a reactionring gear meshing with one of the pinion gears and an output ring gearmeshing with the other pinion gear.

These and other objects and advantages will be more apparent from thefollowing description and drawings in which:

FIG. 1 is a cross sectional elevational view of the planetarygearing;and

FIG. 2 is a cross sectional view taken along line 2 -2 of FIG. 1.

Referring to the drawings and particularly FIG. 1 there is shown astationary housing member 10 and a cover member 12 secured to thestationary housing 10 by a plurality of fasteners 14. A ring gear 16 isformed integral with or otherwise secured to the cover 12. A second ringgear 18 is rotatably mounted in the housing 10 by a pair of ballbearings 20 and 22 and is integrally formed with or otherwise secured toan output shaft 24. An input shaft 26 isrotatably mounted in the cover12 A pairof pinion gears 44 are rotatably mounted on a portion 46 of theeccentric shaft 40 and mesh with the ring gear 18. A second pair ofpinion gears 48 are mounted on another portion 50 of the eccentric shaft40 and mesh with the ring gear 16. The center 44a of pinion gear 44 islocated radiallyoutward of the center 48a of the pinion gear 48.. Thepitch diameter A of the pinion gear 44 is therefore eccentric to thepitch diameter B'of the pinion gear 48. A pair of long pinion gears 52are mounted on the idler shafts 42 in a position such that the centers52a thereof are located on the planet to permit the pinion gears 52 tomesh with the pinion gears 44 and 48 at mesh points which are tangentpoints of the pinion pitch diameters.

- Because each pinion meshes with two gears all of the gears in thecompound planetary gearing arrangement described above have a standardtooth form so that the gear members can be manufactured on'conventionalgear cutting machines. The gears also have the same d'iametral pitch.

The ring gear 18 has more teeth than the ring gear 16 and since thetooth forms of these gears are standard and the diametral pitches areequal, the diameter of the ring gear 18 is larger than the diameter ofthe ring gear 16. In'the preferred embodiment the ring gear 18 has twomore teeth than the ring gear 16 so that a high gear ratio is presentbetween the input shaft 26 and the outputshaft 24. If the ring gear 18has 57 teeth and the ring gear 16 has 55 teeth, the input shaft 26 willhave to be rotated 28.5 revolutions to obtain one revolution of theoutput shaft 24. I

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is, therefore, to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

l. A speed change mechanism comprising; a stationary housing; an inputshaft rotatably mounted in said housing; planet carrier means drivinglyconnected with said input shaft and including first and second mountingmeans eccentric to each other; an output shaft rotatably journaled insaid housing; a first ring gear drivingly connected with said outputshaft; a second ring gear secured to said housing; a first planet pinionrotatably on said first mounting means and meshing with said first ringgear; a second planet pinion rotatably mounted on said second mountingmeans with the center line thereof in a position eccentric with saidfirst planet pinion and meshing with said second ring gear; and a thirdplanet pinion rotatably mounted on said carrier means and meshing withsaid first and second planet pinions at points tangent to the pitchdiameters of said first and second planet pinions to transmit rotarymotion from one of said planet pinions to said other of said planetpinions.

2. A speed change mechanism comprising housing means; input means;output means; carrier means drivingly connected with said input meansincluding eccentric pinion mounting shaft means, first pinion meanshaving a standard tooth form rotatably mounted on said eccentric pinionmounting shaft means; second pinion means having a standard tooth formrotatably mounted on said eccentric pinion mounting shaft meanseecentrically relative to said first pinion means; first ring gear meanshaving a standard tooth form and meshing with said first pinion meansand secured to said housing means; second ring gear means having astandard tooth form and meshing with said second pinion means and beingdrivingly connected with said output means; and idler gear means havinga standard tooth form and meshing with said first and second pinionmeans at points tangent to the pitch diameters thereof to transmitrotation from one pinion means to the other pinion means.

3. A speed change mechanism comprising a stationary housing; an inputshaft rotatably mounted in said housing; planet carrier means drivinglyconnected with said input shaft and including an eccentric shaft havingeccentric mounting means; an output shaft rotatably 5 journaled in saidhousing; a first ring gear drivingly connected with said output shaft; asecond ring gear secured to said housing; a first planet pinionrotatably on said eccentric shaft and meshing with said first ring gear;a second planet pinion rotatably mounted on said eccentric shaft withthe center line thereof in a position eccentric with said first planetpinion and meshing with said second ring gear; a third planet pinionrotatably mounted on said carrier means and meshing with said first andsecond planet pinions at points tangent to the pitch diameters of saidfirst and second planet pinions to transmit rotary motion from one ofsaid planet pinions to said other of said planet pinions; and all ofsaid gears having a standard tooth profile and the same diametral pitch.

1. A speed change mechanism comprising; a stationary housing; an inputshaft rotatably mounted in said housing; planet carrier means drivinglyconnected with said input shaft and including first and second mountingmeans eccentric to each other; an output shaft rotatably journaled insaid housing; a first ring gear drivingly connected with said outputshaft; a second ring gear secured to said housing; a first planet pinionrotatably on said first mounting means and meshing with said first ringgear; a second planet pinion rotatably mounted on said second mountingmeans with the center line thereof in a position eccentric with saidfirst planet pinion and meshing with said second ring gear; and a thirdplanet pinion rotatably mounted on said carrier means and meshing withsaid first and second planet pinions at points tangent to the pitchdiameters of said first and second planet pinions to transmit rotarymotion from one of said planet pinions to said other of said planetpinions.
 2. A speed change mechanism comprising housing means; inputmeans; output means; carrier means drivingly connected with said inputmeans including eccentric pinion mounting shaft means, first pinionmeans having a standard tooth form rotatably mounted on said eCcentricpinion mounting shaft means; second pinion means having a standard toothform rotatably mounted on said eccentric pinion mounting shaft meanseccentrically relative to said first pinion means; first ring gear meanshaving a standard tooth form and meshing with said first pinion meansand secured to said housing means; second ring gear means having astandard tooth form and meshing with said second pinion means and beingdrivingly connected with said output means; and idler gear means havinga standard tooth form and meshing with said first and second pinionmeans at points tangent to the pitch diameters thereof to transmitrotation from one pinion means to the other pinion means.
 3. A speedchange mechanism comprising a stationary housing; an input shaftrotatably mounted in said housing; planet carrier means drivinglyconnected with said input shaft and including an eccentric shaft havingeccentric mounting means; an output shaft rotatably journaled in saidhousing; a first ring gear drivingly connected with said output shaft; asecond ring gear secured to said housing; a first planet pinionrotatably on said eccentric shaft and meshing with said first ring gear;a second planet pinion rotatably mounted on said eccentric shaft withthe center line thereof in a position eccentric with said first planetpinion and meshing with said second ring gear; a third planet pinionrotatably mounted on said carrier means and meshing with said first andsecond planet pinions at points tangent to the pitch diameters of saidfirst and second planet pinions to transmit rotary motion from one ofsaid planet pinions to said other of said planet pinions; and all ofsaid gears having a standard tooth profile and the same diametral pitch.